11_NumberToPronunciation

using System;

class NumberToPronunciation
{
    static void Main()
    {
        int digit;

        Console.Write("Please enter а number into the range [0..999]: ");
        string str = Console.ReadLine();

        if (!int.TryParse(str, out digit))
        {
            Console.WriteLine("Invalid number: {0}", str);
        }
        else
        {
            while (digit < 0 || digit > 999)
            {
                Console.WriteLine("Please enter correct number!");
                string strSecond = Console.ReadLine();

                if (!int.TryParse(strSecond, out digit))
                {
                    Console.WriteLine("Invalid number: {0}", strSecond);
                }
            }

            int hundreds = digit / 100;
            int tens = (digit / 10) % 10;
            int tensBigger = digit % 100; //Tens used to check whether they are more or less than 20
            int units = (tensBigger) % 10;

            string[] numberText = { "zero", "one", "two", "three", "four", "five", "six", "seven", "eight", "nine", "ten", "eleven", "twelve", "thirteen", "fourteen", "fifteen", "sixteen", "seventeen", "eitheen", "nineteen" };

            string[] tensText = { "twenty", "thirty", "fourthy", "fifthy", "sixty", "seventy", "eithy", "ninety" };

            string pronunciation = "";
            string andHundreds = "";

            // Get text only for numbers between 0 and 19
            if (digit >= 0 && digit <= 19)
            {
                pronunciation += numberText[digit];
            }
            else
            {
                if (hundreds > 0)
                {
                    pronunciation += numberText[hundreds] + " " + "hundred";
                    andHundreds = " and ";
                }

                if (tens > 0)
                {
                    if (tensBigger > 20)
                    {
                        // Tens is - 2 because the tensText starts from the text twenty
                        pronunciation += andHundreds + tensText[tens - 2];
                    }
                    else
                    {
                        pronunciation += andHundreds + numberText[tensBigger];
                    }
                }
                else
                {
                    // If tens are 0
                    pronunciation += " and " + numberText[units];
                }

                if (tensBigger > 20 && units > 0)
                {
                    pronunciation += " " + numberText[units];
                }

            }

            Console.WriteLine(char.ToUpper(pronunciation[0]) + pronunciation.Substring(1) + '.');

        }
    }
}